CIE IGCSE Biology Lecture Notes

Introduction

• Video dedicated to CIE IGCSE Biology students.
• Contains key answers for exam success.
• Perfect answer revision guides and courses available on the presenter’s website.

Characteristics of Living Organisms

• Commonly remembered as MRS GREN:
  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition
• Non-living organisms like viruses do not exhibit these features.

Classification Systems

• Purpose: Organizes organisms based on common features.
• Binomial Naming System: Uses genus and species (e.g., Mycobacterium tuberculosis).
• Species Definition: Groups that can breed to produce fertile offspring (e.g., dogs).
• Traditional vs. Modern Systems:
  • Traditional: Based on morphology and anatomy.
  • Modern: Uses DNA sequences and amino acid chains.

Dichotomous Keys

• Used to identify organisms by comparing features and using step-by-step questions.
• Example provided with insects for clarity.

The Five Kingdoms

• Plants, Animals, Protists, Bacteria, Fungi
• Vertebrates: Animals with backbones, classified into mammals, birds, reptiles, fish, and amphibians.
• Invertebrates: Lack backbones, include arthropods.

Plant and Animal Cells

• Shared organelles: Cell membrane, cytoplasm, nucleus, ribosomes, mitochondria.
• Plant-specific: Cell wall, vacuole, chloroplasts.
• Definitions of Eukaryotes (animal cells) and Prokaryotes (bacteria).

Specialized Cells

• Red Blood Cells: Transport oxygen, lack nucleus, biconcave shape.
• Muscle Cells: Contract/relax for movement.
• Ciliated Cells: Waft mucus in respiratory tract.
• Sperm Cells: Reproduction, contain mitochondria for energy.
• Root Hair Cells: Absorb water/nutrients in plants.

Biological Molecules

• Carbohydrates: Monosaccharides & polysaccharides like starch.
• Proteins: Made of amino acids, structural and functional roles.
• DNA Structure: Double helix, bases (A-T, C-G).
• Enzymes: Biological catalysts, affected by temperature and pH.

Photosynthesis

• Equation: CO2 + H2O -> C6H12O6 + O2
• Limiting Factors: Light intensity, carbon dioxide level, temperature.

Plants

• Leaf Structure: Adaptations for photosynthesis (large surface area, chloroplast-rich cells).
• Transpiration: Moves water, influenced by temperature, humidity, wind.

Human Nutrition

• Balanced Diet: Carbohydrates, proteins, fats, vitamins, minerals, water, fiber.
• Vitamin/Mineral Deficiencies: e.g., Vitamin C deficiency causes scurvy.

Digestion

• Enzymes: Amylase (starch), protease (proteins), lipase (fats).
• Teeth: Incisors, canines, premolars, molars.
• Digestive System: Ingestion, digestion, absorption, egestion.

Transport in Plants

• Xylem: Transports water/minerals.
• Phloem: Transports sugars.
• Transpiration Stream: Movement of water from roots to leaves.

Transport in Animals

• Circulatory System: Heart pumps blood, arteries/veins transport it.
• Blood Components: Red blood cells, white blood cells, plasma, platelets.

Immune System

• Pathogen Defense: Skin, stomach acid, tears.
• White Blood Cells: Phagocytes (engulf pathogens), lymphocytes (produce antibodies).
• Vaccinations: Induce immunity by introducing harmless pathogen forms.

Respiration

• Aerobic Respiration: Requires oxygen, produces CO2 and water.
• Anaerobic Respiration: Produces lactic acid (in humans) or ethanol (in yeast).

Excretion

• Kidney Function: Filtration, selective reabsorption, water balance.
• Osmoregulation: Control of water content, related to ADH.

Nervous System

• Reflex Actions: Fast, involuntary responses.
• Eye Structure: Pupil reflex, accommodation for focusing.

Hormones

• Adrenaline: Fight or flight response.
• Insulin and Glucagon: Blood sugar regulation.

Reproduction

• Human Reproductive Systems: Male and female anatomy and functions.
• Fertilization: Gametes (sperm and egg) meeting.

Genetic Inheritance

• Mitosis vs. Meiosis: Mitosis for growth/repair, meiosis for gametes.
• Genetics Vocabulary: Genotype, phenotype, dominant/recessive traits.
• Punnett Squares: Predicts genetic outcomes.

Ecology

• Ecosystems and Communities: Interactions of organisms and environment.
• Food Webs: Energy flow, producers, consumers.
• Human Impact: Pollution, habitat destruction.

Conservation

• Sustainable Development: Resource use without depletion.
• Endangered Species: Conservation efforts, habitat protection.

Applications of Biology

• Genetic Engineering: Producing insulin, modifying plants.
• Microorganisms: Use in food production (yeast in bread/beer).

This guide is comprehensive and covers all important topics discussed in the lecture. Use it for thorough revision and understanding of CIE IGCSE Biology key concepts.